Solid, ionically conducting polymer material, and methods and applications for same

ABSTRACT

The invention features a method of making a battery electrode for an electrochemical cell. The method includes mixing a base polymer with an ion source, and then reacting the base polymer with an electron acceptor in the presence of the ion source to form a solid, ionically conductive polymer material having an ionic conductivity greater than 1×10−4 S/cm at room temperature. The battery electrode is electrochemically active when used in the electrochemical cell.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

(Not applicable)

BACKGROUND OF THE INVENTION

Batteries have become increasingly important in modern society, both inpowering a multitude of portable electronic devices, as well as beingkey components in new green technologies. These new technologies offerthe promise of removing the dependence on current energy sources such ascoal, petroleum products, and natural gas which contribute to theproduction of by-product green-house gases. Furthermore, the ability tostore energy in both stationary and mobile applications is critical tothe success of new energy sources, and is likely to sharply increase thedemand for all sizes of advanced batteries. Especially for batteries forlarge applications, a low base cost of the battery will be key to theintroduction and overall success of these applications.

Conventional batteries have limitations, however. For example, lithiumion and other batteries generally employ a liquid electrolyte which ishazardous to humans and to the environment and which can be subject tofire or explosion. Liquid electrolyte batteries are hermetically sealedin a steel or other strong packaging material which adds to the weightand bulk of the packaged battery. Conventional liquid electrolytesuffers from the build-up of a solid interface layer at theelectrode/electrolyte interface which causes eventual failure of thebattery. Conventional lithium ion batteries also exhibit slow chargetimes and suffer from a limited number of recharges since the chemicalreaction within the battery reaches completion and limits there-chargeability because of corrosion and dendrite formation. The liquidelectrolyte also limits the maximum energy density which starts to breakdown at about 4.2 volts while often 4.8 volts and higher are required inthe new industry applications. Conventional lithium ion batteriesrequire a liquid electrolyte separator to allow ion flow but blockelectron flow, a vent to relieve pressure in the housing, and inaddition, safety circuitry to minimize potentially dangerousover-currents and over-temperatures.

With respect to alkaline batteries which rely on the transport of OH⁻ions to conduct electricity, the electrolyte becomes saturated with ions(e.g., zincate ions during discharge of Zn/MnO₂ batteries) at a certainpoint and eventually the anode becomes depleted of water. Inrechargeable alkaline batteries, the reactions are reversed duringcharge. Formation of the same ions which saturated the electrolyte mayhinder discharging, however. The cathode reaction results in the releaseof the OH⁻ ions. The formation of soluble low valent species (e.g., Mnspecies during discharge of Zn/MnO₂ batteries) can adversely affect theutilization of active material however. Although MnO₂ can theoreticallyexperience 2-electron reduction with a theoretical capacity of 616mAh/g, in practice a specific capacity close to theoretical 2-electrondischarge has not been demonstrated. Crystalline structure rearrangementwith formation of inactive phases and out-diffusion of soluble productslimits cathode capacity.

U.S. Pat. No. 7,972,726 describes the use of pentavalent bismuth metaloxides to enhance overall discharge performance of alkaline cells.Cathode containing 10% AgBiO₃ and 90% electrolytic MnO₂ was shown todeliver 351 mAh/g to 0.8V cut-off at 10 mA/g discharge rate, compared to287 mAh/g for 100% MnO₂ and 200 mAh/g for 100% AgBiO₃. The 351 mAh/gspecific capacity corresponds to 1.13 electron discharge of MnO₂ andrepresents the highest specific capacity delivered at practically usefuldischarge rates and voltage range. Bismuth- or lead-modified MnO₂materials, disclosed in U.S. Pat. Nos. 5,156,934 and 5,660,953, wereclaimed to be capable of delivering about 80% of the theoretical2-electron discharge capacity for many cycles. It was theorized inliterature [Y. F. Yao, N. Gupta, H. S. Wroblowa, J. Electroanal. Chem.,223 (1987), 107; H. S. Wroblowa, N. Gupta, J. Electroanal. Chem., 238(1987) 93; D. Y. Qu, L. Bai, C. G. Castledine, B. E. Conway, J.Electroanal. Chem., 365 (1994), 247] that bismuth or lead cations canstabilize crystalline structure of MnO₂ during discharge and/or allowfor 2-electron reduction to proceed via heterogeneous mechanisminvolving soluble Mn²⁺ species. Containing said Mn²⁺ species seems to bethe key for attaining high MnO₂ utilization and reversibility. In highcarbon content (30-70%) cathodes per U.S. Pat. Nos. 5,156,934 and5,660,953, the resulting highly porous structure was able to absorbsoluble species. However, there is no data to suggest that a completecell utilizing these cathodes was built or that this worked using a Znanode.

Accordingly, polymer electrolyte which prevents 1) the dissolution ofions which would otherwise saturate the electrolyte and 2) thedissolution and transport of low-valent species, would improveutilization and rechargeability of alkaline batteries. In addition, ithas been suggested [M. Minakshi, P. Singh, J. Solid State Electrochem,16 (2012), 1487] that Li insertion can stabilize the MnO₂ structure uponreduction and enable recharegeablity. A polymer engineered to conductLi⁺ and OH⁻ ions, opens the possibility to tune MnO₂ discharge mechanismin favor of either proton or lithium insertion, which can serve as anadditional tool to improve life cycle.

Further, while the battery technology for many advanced applications isLithium Ion (Li-ion), increased demands for higher energy density, bothin terms of volumetric (Wh/L) for portable devices, and gravimetric(Wh/kg) for electric vehicles and other large applications have shownthe necessity for accessing technologies well beyond the currentcapabilities of Li-ion cells. One such promising technology is Li/sulfurbatteries. A sulfur based cathode is enticing because of the hightheoretical energy density (1672 mAh/g) which is ˜10× better than thecurrent Li-ion metal oxide cathode active materials. Sulfur is alsoexciting because it is a very abundant, low cost, environmentallyfriendly material, unlike many current Li-ion battery materials, such asLiCoO₂.

Recently, there has been a great amount of activity in Li/sulfur batteryresearch, with advances in the capacity and cycle life of rechargeableLi/sulfur cells. Activity has included modifications to the cathode,anode, electrolyte and separator, all with the goal of reducing thepolysulfide shuttle and thereby improving cell performance. Applicationsof this research to sulfur cathodes has focused in two main areas: 1)the use of engineered materials to surround and contain the sulfur andsoluble lithiated products, for example see: U.S. Patent Application2013/0065128, and 2) the use of conductive polymers which react withsulfur to produce a “sulfurized” composite cathode material. Examples of“sulfurized-polymer” include reaction products from high temperatureexposure of sulfur with polyacrylonitrile (PAN) [see: Jeddi, K., et. al.J. Power Sources 2014, 245, 656-662 and Li, L., et. al. J. Power Sources2014, 252, 107-112]. Other conductive polymer systems used in sulfurcathodes include polyvinylpyrrolidone (PVP) [see: Zheng, G., et. al.Nano Lett. 2013, 13, 1265-1270] and polypyrrole (PPY) [see: Ma, G., et.al. J. Power Sources 2014, 254, 353-359]. While these methods have metwith various degrees of success in limiting the polysulfide shuttlemechanism, they all rely on the use of expensive materials which are notwell suited to large scale manufacturing.

BRIEF SUMMARY OF THE INVENTION

A solid, ionically conducting polymer material is provided having veryhigh ionic diffusivity and conductivity at room temperature and over awide temperature range. The solid ionic polymer material is useful as asolid electrolyte for alkaline batteries and is also is useful as acomponent to make electrodes for alkaline batteries. The material is notlimited to battery applications but is more broadly applicable for otherpurposes such as alkaline fuel cells, supercapacitors, electrochromicdevices, sensors and the like. The polymer material is non-flammable andself-extinguishes, which is especially attractive for applications whichotherwise might be flammable. In addition the material is mechanicallystrong and can be manufactured using high volume polymer processingtechniques and equipment which themselves are known in the art.

In one aspect of the invention the solid ionically conducting polymermaterial serves as an electrolyte to transmit OH⁻ ions in an alkalinebattery. The alkaline battery may comprise various battery chemistriesincluding, but not limited, Zn/MnO₂, Zn/Ni, FE/NI, Zn/AIR, Ni/MetalHydride, Silver Oxide, Metal/Air and others known in the art. Thezinc/manganese oxide (Zn/MnNO₂) chemistry is the most widely used forconsumer alkaline batteries.

A solid ionic polymer electrolyte for lithium ion batteries includingthe solid, ionically conducting polymer material is disclosed inco-pending U.S. patent application Ser. No. 13/861,170 filed Apr. 11,2013 and assigned to the same Assignee as the present invention.

In another aspect of the invention, the solid, ionically conductingpolymer material is employed to form the cathode, electrolyte and anodeof an alkaline battery. The three layers of the battery are solid andcan be co-extruded to efficiently form the battery structure. Theindividual layers may also be or may alternatively be separatelyextruded or otherwise formed and layered together to form the batterystructure.

The solid, ionically conducting polymer material includes a basepolymer, a dopant and at least one compound including an ion source. Thedopant includes an electron donor, an electron acceptor or an oxidant.In one embodiment for batteries with OH— chemistry, the base polymer canbe a polyphenylene sulfide, a polyether ether ketone also known as PEEK,or a liquid crystal polymer. In this embodiment, the dopant is anelectron acceptor such as, for nonlimiting examples,2,3-dicloro-5,6-dicyano-1,4-benzoquinone, TCNE, sulfur trioxide orchloranil. Other dopants acting as electron acceptors or containingfunctional groups capable to accept electrons can be employed. Thecompound including an ion source includes compounds containing hydroxylions or materials chemically convertible to compounds containinghydroxyl ions including, but not limited to, hydroxides, oxides, saltsor mixtures thereof, and more specifically Li2O, Na2O, MgO, CaO, ZnO,LiOH, KOH, NaOH, CaCl2, AlCl3, MgCl2, LiTFSI (lithiumbis-trifluoromethanesulfonimide), LiBOB (Lithium bis(oxalate)borate) ora mixture of the preceding two components.

The solid ionically conducting polymer material exhibits carbon 13 NMR(detection at 500 MHz) chemical shift peaks at about 172.5 ppm, 143.6ppm, 127.7 ppm, and 115.3 ppm. A similar carbon 13 NMR scan of theelectron acceptor shows chemical shift peaks at about 195 ppm, and 107.6ppm in addition to the chemical shift peaks at about 172.5 ppm, 143.6ppm, 127.7 ppm, and 115.3 ppm. In other words, the reaction between thebase polymer and the electron acceptor appears to eliminate the chemicalshift peaks at about 195 ppm, and 107.6 ppm. In addition, the ¹³C NMRspectrum of the solid ionically conducting polymer movement in the mainpeak (dominated by the aromatic carbon) in going from the base polymerto the solid ionically conducting polymer. The chemical shift of thedominant peak in the solid ionically conducting polymer is greater thanthe chemical shift of the dominant peak in the base polymer.

The material has crystallinity index of at least or greater than about30%.

The compound including the ion source is in a range of 10 wt. % to 60wt. %.

The dopant molar ratio is in the range of about 1-16.

The material has an ionic conductivity of at least 1×10⁻⁴ S/cm at roomtemperature of between 20° C. to 26° C.

The materials ha a tensile strength in the range of 5-100 MPa, a Modulusof Elasticity in the range of 0.5-3.0 GPa, and Elongation in the rangeof 0.5-30%

The material has an OH-diffusivity of greater than 10⁻¹¹ cm²/S at roomtemperature of between 20° C. to 26° C.

The batteries with OH⁻ chemistry may be rechargeable ornon-rechargeable.

In another aspect, the invention provides a rechargeable alkalinebattery including an anode; a cathode; and an electrolyte; wherein atleast one of anode, the cathode and the electrolyte include a solid,ionically conducting polymer material.

In one embodiment of said battery, the battery comprises an anode; acathode; and wherein at least one of the anode, and the cathode comprisea solid, ionically conducting polymer material. The battery can berechargeable or primary. The battery further comprises an electrolyte,and the electrolyte can comprise the solid, ionically conducting polymermaterial. The battery can alternatively or additionally further comprisean electrolyte, and said electrolyte can be alkaline. As the solid,ionically conducting polymer can conduct a plurality of OH⁻ ions and hasan OH⁻ diffusivity of greater than 10-11 cm²/sec at a temperature in arange of 20° C. to 26° C. it is particularly well suited for use onalkaline battery electrodes.

The solid, ionically conducting polymer material is formed from areactant product comprising a base polymer, an electron acceptor, and acompound including a source of ions. The solid, ionically conductingpolymer material can be used as an electrolyte in either the anode orcathode. If used in a battery the cathode of said battery can comprisean active material selected from the group comprising ferrate, ironoxide, cuprous oxide, iodate, cupric oxide, mercuric oxide, cobalticoxide, manganese oxide, lead dioxide, silver oxide, oxygen, nickeloxyhydroxide, nickel dioxide, silver peroxide, permanganate, bromate,silver vanadium oxide, carbon monofluoride, iron disulfide, iodine,vanadium oxide, copper sulfide, sulfur or carbon and combinationsthereof. The anode of said battery can comprise an active materialselected from the group comprising lithium, magnesium, aluminum, zinc,chromium, iron, nickel, tin, lead, hydrogen, copper, silver, palladium,mercury, platinum or gold, and combinations thereof, and alloyedmaterials thereof.

In an alkaline battery where the cathode comprises manganese dioxide,and the anode comprises zinc. The manganese dioxide can take the form ofa β-MnO₂ (pyrolusite), a ramsdellite, a γ-MnO₂, a ε-MnO₂, a λ-MnO₂, anelectrolytic manganese dioxide (EMD), and a chemical manganese dioxide(CMD) and a combination of the proceeding forms. Further, at least oneof the anode and cathode can comprise particles of active material andthe solid, ionically conductive polymer material can encapsulate atleast one particle of the active material or all of the active material.Such cathodes have shown specific capacity greater than 400 mAh/g, 450mAh/g, and 500 mAh/g.

The battery can alternatively further comprise an electricallyconductive additive and/or a functional additive in either the anode orcathode. The electrically conductive additive can be selected from thegroup comprising a carbon black, a natural graphite, a syntheticgraphite, a graphene, a conductive polymer, a metal particle, and acombination of at least two of the preceding components. The functionaladditive can be selected from the group comprising bismuth, ZnO, MgO,CaO, SnO₂, Na₂SnO₃, and ZnSO₄.

The battery electrodes (anode or cathode) can composite structure whichcan be formed by a process such as injection molding, tube extrusion andcompression molding. In one embodiment of making the solid, ionicallyconductive polymer material the base polymer is oxidatively doped in thepresence of an ion source. The ion source is a compound including atleast one hydroxyl group or convertible to a compound containing atleast one hydroxyl group, or alternatively selected from the groupconsisting of a LiOH, a Li₂O or a mixture of the preceding twocomponents. The base polymer is selected from the group comprising aliquid crystal polymer, a polyether ether ketone (PEEK), and apolyphenylene sulphide (PPS), or a semicrystalline polymer with acrystallinity index of greater than 30%, and combinations thereof. Theelectron acceptor which reacts with the base polymer in the presence ofthe ion source can be selected from the group comprising 2,3,dicloro-5,6-dicyano-1,4-benzoquinone, TCNE, sulfur trioxide or chloraniland combinations thereof. The method can additionally include a heatingstep to further the reaction. An electrochemically active material canbe added to the mixing step and if so added is encapsulated by thereacted ionically conductive polymer. Such a battery with a MnO₂cathode, zinc anode and an alkaline electrolyte wherein the alkalinebattery is characterized by a flat discharge curve above 1 V, and havinga voltage drop less than 0.3V between 5 and 95% depth of discharge.

The solid, ionically conductive polymer material can also be useful as aseparator film, as it is electrically non-conductive, and ionicallyconductive. Therefore the solid, ionically conductive polymer materialcast or otherwise rendered as a film can be used as a separatorpositioned between an anode and cathode. In addition, the solid,ionically conductive polymer material can be coated onto an electrode tofunction as a separator or alternatively to isolate the electrode or anelectrode component from another battery component such as an aqueouselectrolyte. The solid, ionically conductive polymer material enablesionic communication between such an isolated component despite it beingphysically separated, and electrically segmented from the rest of thebattery component. The material can also comprise an aggregated or castagglomeration of small particles of the solid, ionically conductivepolymer material. Such an aggregation can take any shape but include anengineered porosity while possessing an engineered surface area.Fillers, such as hydrophobic materials can be mixed in the material toprovide desirable physical properties such as low effective aqueousporosity. Catalysts can be added to the solid, ionically conductivepolymer material to enable a combination of catalysis and ionicconductivity, such as required in an air electrode for a metal/airbattery. Thus the solid, ionically conductive polymer material caninclude a low or very high surface area, and or a low or very highporosity. Shapes such as an annulus and other moldable shapes can beengineering with desired physical properties with the ionic conductivityof the solid, ionically conductive polymer material are enabled by theinvention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 exemplarily shows a resulting formula for the crystalline polymerof the present invention.

FIG. 2 exemplarily illustrates a dynamic scanning calorimeter curve of asemicrystalline polymer.

FIG. 3 exemplarily illustrates formulations which were investigated foruse with the invention.

FIG. 4 shows a schematic illustration of amorphous and crystallinepolymers.

FIG. 5 exemplarily illustrates a chemical diagram of2,3-dicyano-5,6-dichlorodicyanoquinone (DDQ) as a typical electronacceptor dopant for use in the invention.

FIG. 6 exemplarily illustrates a plot of the conductivity of theionically conductive polymer according to the invention in comparisonwith a liquid electrolyte and a polyethylene oxide lithium saltcompound.

FIG. 7 exemplarily illustrates the mechanical properties of theionically conducting film according to the invention.

FIG. 8 exemplarily illustrates possible mechanisms of conduction of thesolid electrolyte polymer according to the invention.

FIG. 9 exemplarily shows a UL94 flammability test conducted on a polymeraccording to the invention.

FIG. 10 exemplarily shows a plot of volts versus current of an ionicallyconductive polymer according to the invention versus lithium metal.

FIG. 11 exemplarily illustrates a schematic of extruded ionicallyconductive electrolyte and electrode components according to theinvention.

FIG. 12 exemplarily illustrates the solid state battery according to theinvention where electrode and electrolyte are bonded together.

FIG. 13 exemplarily illustrates a final solid state battery according tothe invention having a new and flexible form.

FIG. 14 exemplarily illustrates a method of the invention includingsteps for manufacturing a solid state battery using an extruded polymer.

FIG. 15 exemplarily illustrates the extrusion process according to theinvention.

FIG. 16 exemplarily illustrates a schematic representation of anembodiment according to the invention.

FIG. 17 exemplarily illustrates an alkaline battery having three layersof the invention.

FIG. 18 exemplarily illustrates a comparison of process steps forstandard Li-ion cathode manufacturing with those for extrusion of thecomposite polymer-sulfur cathode of the invention.

FIG. 19 exemplarily illustrates OH⁻ diffusivity at room temperature in asolid polymer electrolyte of the invention;

FIG. 20 exemplarily illustrates lithium diffusivity at room temperaturein a solid polymer electrolyte of the invention.

FIG. 21 exemplarily illustrates voltage profile of cell of the inventionper example 2 as a function of specific capacity of MnO₂ at 0.5 mA/cm²discharge rate.

FIG. 22 exemplarily illustrates voltage profile of cell of the inventionper example 3 as a function of specific capacity of MnO₂ at C/9 rate (35mA/g).

FIG. 23 exemplarily illustrates specific capacity of MnO₂ as a functionof cycle number in the cells of the invention per example 4.

FIG. 24 exemplarily illustrates discharge curve of coin cell of theinvention per example 5 as a function of test time.

FIG. 25 exemplarily illustrates voltage profile of the cell of theinvention per example 6 as a function of test time.

FIG. 26 exemplarily illustrates discharge curve of coin cells of theinvention per example 7 as a function of discharge capacity.

FIG. 27 exemplarily illustrates a potentiodynamic scan at 1 mV/s ofanode of the present invention (curve A) and control Al foil (curve B)in ZnSO₄ electrolyte. Zn foil was used as counter electrode.

FIG. 28 illustrates the conductivity for various solid polymerelectrolyte samples made by mixing polymer and compound comprising ionsource in various proportions and doping using DDQ.

FIG. 29 illustrates discharge curves for alkaline button cells at 10mA/g rate per prior art.

FIG. 30 exemplarily illustrates voltage profile of a cell of theinvention per comparative example 12 at 35 mA/g constant currentdischarge as a function of specific capacity of MnO₂.

FIG. 31 exemplarily illustrates voltage profile of a cell of theinvention per example 13 as a function of specific capacity of MnO₂.

FIG. 32 exemplarily illustrates a voltage profile of cell of theinvention per example 14 as a function of specific capacity of MnO₂ incomparison with a Duracell Coppertop cell.

FIG. 33 exemplarily illustrates a voltage profile of a cell of theinvention per example 15 as a function of specific capacity of MnO₂ incomparison with a Duracell Coppertop cell.

FIG. 34 exemplarily illustrates a first discharge voltage curve forLi/Ionic polymer-sulfur cell of the present invention.

FIG. 35 exemplarily illustrates a discharge capacity curve plotted as afunction of cycle number for Li/Ionic polymer-sulfur cell of the presentinvention.

FIG. 36 exemplarily illustrates a comparison of first discharge forliterature example Li/Sulfur-CMK-3 with Li/Ionic polymer-sulfur ofpresent invention.

FIG. 37 illustrates a charge/discharge voltage curves for aLi/sulfur-poly(pyridinopyridine) cell from the prior art.

DETAILED DESCRIPTION OF THE INVENTION

This application is a continuation of U.S. patent application Ser. No.14/559,430, filed Dec. 3, 2014 which claims priority to U.S. ProvisionalApplication No. 61/911,049, entitled Polymer Electrolyte for AlkalineBatteries and electrodes Comprising the Electrolyte, filed Dec. 3, 2013which is hereby incorporated by reference for all purposes.

The invention comprises a solid, ionically conductive polymer materialincluding a base polymer, a dopant, and at least one compound includingan ion source. The polymer material has a capacity for ionic conductionover a wide temperature range including room temperature. It is believedthat ion “hopping” occurs from a high density of atomic sites. Thus, thepolymer material can function as a means for supplying ions and hassignificant material strength.

For the purposes of this application, the term “polymer” refers to apolymer having a crystalline or semi-crystalline structure. In someapplications, the solid, ionically conductive polymer material can bemolded into shapes which can be folded back on itself allowing for newphysical formats depending on the application. The base polymer isselected depending upon the desired properties of the composition inrelation to the desired application.

For purposes of the application, the term “dopant” refers to electronacceptors or oxidants or electron donors. The dopant is selecteddepending upon the desired properties of the composition in relation tothe desired application.

Similarly, the compound including an ion source is selected dependingupon the desired properties of the composition in relation to thedesired application.

I. Li⁺ Chemistries

In one aspect, the invention relates to a solid polymer electrolyteincluding the solid, ionically conductive polymer material in a lithiumion battery.

In this aspect, the base polymer is characterized as having acrystallinity value of between 30% and 100%, and preferably between 50%and 100%. The base polymer has a glass transition temperature of above80° C., and preferably above 120° C., and more preferably above 150° C.,and most preferably above 200° C. The base polymer has a meltingtemperature of above 250° C., and preferably above 280° C., and morepreferably above 320° C. The molecular weight of the monomeric unit ofthe base polymer of the invention is in the 100-200 gm/mol range and canbe greater than 200 gm/mol. FIG. 1 shows the molecular structure of anexemplary base polymer, wherein the monomeric unit of the base polymerhas a molecular weight of 108.16 g/mol. FIG. 2 exemplarily illustrates adynamic scanning calorimeter curve of an exemplary semicrystalline basepolymer. FIG. 3 illustrates exemplary formulations for the solid,ionically conducting polymer material in this aspect of the inventionwhere DDQ is the dopant. Typical materials that can be used for the basepolymer include liquid crystal polymers and polyphenylene sulfide alsoknown as PPS, or any semi-crystalline polymer with a crystallinity indexgreater than 30%, and preferably greater than 50%. In one embodiment,the invention uses a “crystalline or semi-crystalline polymer”,exemplarily illustrated in FIG. 4, which typically is above acrystallinity value of 30%, and has a glass transition temperature above200° C., and a melting temperature above 250° C.

In this aspect, the dopant is an electron acceptor, such as, fornon-limiting examples, 2,3-dicyano-5,6-dichlorodicyanoquinone(C₈Cl₂N₂O₂) also known as DDQ, Tetracyanoethylene(C₆N₄) known as TCNE,and sulfur trioxide (SO₃). A preferred dopant is DDQ. FIG. 5 provides achemical diagram of this preferred dopant. It is believed that thepurpose of the electron acceptor is two-fold: to release ions fortransport mobility, and to create polar high density sites within thepolymer to allow for ionic conductivity. The electron acceptor can be“pre-mixed” with the initial ingredients and extruded withoutpost-processing or alternatively, a doping procedure such as vapordoping can be used to add the electron acceptor to the composition afterthe material is created.

Typical compounds including an ion source for use in this aspect of theinvention include, but are not limited to, Li₂O, LiOH, ZnO, TiO₂, Al₃O₂,and the like. The compounds containing appropriate ions which are instable form can be modified after creation of the solid, polymerelectrolytic film.

Other additives, such as carbon particles nanotubes and the like, can beadded to the solid, polymer electrolyte including the solid, ionicallyconducting material to further enhance electrical conductivity orcurrent density.

The novel solid polymer electrolyte enables a lighter weight and muchsafer architecture by eliminating the need for heavy and bulky metalhermetic packaging and protection circuitry. A novel solid polymerbattery including the solid polymer electrolyte can be of smaller size,lighter weight and higher energy density than liquid electrolytebatteries of the same capacity. The novel solid polymer battery alsobenefits from less complex manufacturing processes, lower cost andreduced safety hazard, as the electrolyte material is non-flammable. Thenovel solid polymer battery is capable of cell voltages greater than 4.2volts and is stable against higher and lower voltages. The novel solidpolymer electrolyte can be formed into various shapes by extrusion (andco-extrusion), molding and other techniques such that different formfactors can be provided for the battery. Particular shapes can be madeto fit into differently shaped enclosures in devices or equipment beingpowered. In addition, the novel solid polymer battery does not require aseparator, as with liquid electrolyte batteries, between the electrolyteand electrodes. The weight of the novel solid polymer battery issubstantially less than a battery of conventional construction havingsimilar capacity. In some embodiments, the weight of the novel solidpolymer battery can be less than half the weight of a conventionalbattery.

In another aspect of the invention, a solid polymer electrolyteincluding the solid, ionically conducting polymer material is in theform of an ionic polymer film. An electrode material is directly appliedto each surface of the ionic polymer film and a foil charge collector orterminal is applied over each electrode surface. A light weightprotective polymer covering can be applied over the terminals tocomplete the film based structure. The film based structure forms a thinfilm battery which is flexible and can be rolled or folded into intendedshapes to suit installation requirements.

In yet another aspect of the invention, a solid polymer electrolyteincluding the solid, ionically conducting polymer material is in theform of an ionic polymer hollow monofilament. Electrode materials andcharge collectors are directly applied (co-extruded) to each surface ofthe solid, ionically conductive polymer material and a terminal isapplied at each electrode surface. A light weight protective polymercovering can be applied over the terminals to complete the structure.The structure forms a battery which is thin, flexible, and can be coiledinto intended shapes to suit installation requirements, including verysmall applications.

In still another aspect of the invention, a solid polymer electrolyteincluding the solid, ionically conducting polymer material has a desiredmolded shape. Anode and cathode electrode materials can be disposed onrespective opposite surfaces of the solid polymer electrolyte to form acell unit. Electrical terminals can be provided on the anode and cathodeelectrodes of each cell unit for interconnection with other cell unitsto provide a multi cell battery or for connection to a utilizationdevice.

In aspects of the invention relating to batteries, the electrodematerials (cathode and anode) can be combined with a form of the novelsolid, ionically conductive polymer material to further facilitate ionicmovement between the two electrodes. This is analogous to a conventionalliquid electrolyte soaked into each electrode material in a conventionlithium-ion battery.

Films of solid, ionically conducting polymer materials of the presentinvention have been extruded in thickness ranging upwards from 0.0003inches. The ionic surface conductivity of the films has been measuredusing a standard test of AC-Electrochemical Impedance Spectroscopy (EIS)known to those of ordinary skill in the art. Samples of the solid,ionically conducting polymer material film were sandwiched betweenstainless steel blocking electrodes and placed in a test fixture.AC-impedance was recorded in the range from 800 KHz to 100 Hz using aBiologic VSP test system to determine the electrolyte conductivity. Theresults of the surface conductivity measurements are illustrated in FIG.6. The conductivity of solid, ionically conductive polymer material filmaccording to the invention (Δ) is compared with that of trifluoromethanesulfonate PEO (□) and a liquid electrolyte made up of a Li salt soluteand a EC:PC combination solvent using a Celgard separator (◯). Theconductivity of the solid, ionically conducting polymer material filmaccording to the invention tracks the conductivity of the liquidelectrolyte and far surpasses that of trifluoromethane sulfonate PEO atthe lower temperatures. Further, unlike PEO electrolytes, thetemperature dependence of the conductivity for inventive polymermaterial does not display a sharp increase above its glass transitiontemperature, associated with chain mobility, as described byVogel-Tamman-Fulcher behavior activated by temperature. Therefore,segmental movement as the ion-conduction mechanism in the inventivepolymer material is unlikely. Furthermore, this demonstrates that theinventive polymer material has similar ionic conductivity to liquidelectrolytes.

FIG. 7 shows the mechanical properties of the solid, ionicallyconductive polymer material films of the invention. The mechanicalproperties were evaluated using the Institute for Interconnecting andPackaging Electronic Circuits IPC-TM-650 Test Methods Manual 2.4.18.3.In the tensile strength versus elongation curve of FIG. 7, the “ductilefailure” mode indicates that the material can be very robust.

The solid, ionically conductive polymer material of the invention offersthree key advantages in its polymer performance characteristics: (1) Ithas an expansive temperature range. In lab-scale testing, thecrystalline polymer has shown high ionic conductivity both at roomtemperature and over a wide temperature range. (2) It is non-flammable.The polymer self-extinguishes, passing the UL-V0 Flammability Test. Theability to operate at room temperature and the non-flammablecharacteristics demonstrate a transformative safety improvement thateliminates expensive thermal management systems. (3) It offers low-costbulk manufacturing. Rather than spraying the polymer onto electrodes,the polymer material can be extruded into a thin film via a roll-to-rollprocess, an industry standard for plastics manufacturing. After the filmis extruded, it can be coated with the electrode and charge collectormaterials to build a battery “from the inside out.” This enables thin,flexible form factors without the need for hermetic packaging, resultingin easy integration into vehicle and storage applications at low cost.

It is believed that the solid, ionically conducting polymer material ofthe present invention creates a new ionic conduction mechanism thatprovides a higher density of sites for ionic transport and allows theconducting material to maintain higher voltages without risk of thermalrunaway or damage to ion transport sites from, for example, lithiation.This characteristic enables the solid, ionically conducting polymermaterial to be durable for anode materials and higher voltage cathodethin-film applications, resulting in higher energy densities forbatteries which may be used in vehicle and stationary storageapplications. The ability to maintain high voltages within a solid,ionically conductive polymer material which is mechanically robust,chemical and moisture resistant, and nonflammable not only at roomtemperature, but over a wide range of temperatures, allows integrationwith high performance electrodes without costly thermal and safetymechanisms employed by the industry today.

Batteries employing the solid polymer electrolyte including the solid,ionically conductive polymer material of the invention are characterizedby an energy density improvement over current commercially availableelectrolytes, as well as a performance range of −40° C. to 150° C. withminimal conductivity degradation. The solid polymer electrolyte can beextruded by a process that produces polymers of a thickness of 6microns, which enables thin-film formats under commercial manufacturingconditions at batch scale. Further, such extrusion processes enableshigh throughput, low-cost manufacturing lines for the production of thesolid polymer electrolyte, and the processes can be integrated into avariety of product lines, including lithium and zinc batterymanufacture. Battery costs can be reduced by up to 50%.

In addition, the solid, ionically conductive polymer material is notlimited to use in batteries, but can be used in any device orcomposition that includes an electrolyte material. For example, thenovel solid, ionically conductive polymer material can be used inelectrochromic devices, electrochemical sensors, supercapacitors andfuel cells. FIG. 8 shows possible mechanisms of conduction of the solid,ionically conducting polymer material in a solid polymer electrolyteaspect of the invention. Charge carrier complexes are set up in thepolymer as a result of the doping process.

Flammability of the solid polymer electrolyte including the solid,ionically conductive polymer material of the invention was tested usinga UL94 flame test. For a polymer to be rated UL94-V0, it must“self-extinguish” within 10 seconds and ‘not drip”. The solid polymerelectrolyte was tested for this property and it was determined that itself-extinguished with 2 seconds, did not drip, and therefore easilypassed the V0 rating. FIG. 9 shows pictures of the result.

In addition to the properties of ionic conductivity, flame resistance,high temperature behavior, and good mechanical properties, it ispreferable that the solid polymer electrolyte including the solid,ionically conductive polymer material of the invention iselectrochemically stable at low and high potentials. The traditionaltest for the electrochemical stability is cyclic voltammetry, whenworking electrode potential is ramped linearly versus time. In thistest, the polymer is sandwiched between a lithium metal anode andblocking stainless steel electrode. A voltage is applied and it is sweptpositively to a high value (greater than 4 volts vs. Li) for stabilitytowards oxidation and negatively to a low value (0V vs. Li or less) forstability towards reduction. The current output is measured to determineif any significant reaction occurs at the electrode interface. Highcurrent output at high positive potential would signify oxidationreaction taking place, suggesting instability with cathode materialsoperating at these or more positive potentials (such as many metaloxides). High current output at low potentials would signify that areduction reaction takes place, suggesting instability with anodesoperating at these or more negative potentials (such as metal Li orlithiated carbon). FIG. 10 shows a plot of voltage versus current for asolid polymer electrolyte including the solid, ionically conductivepolymer material according to the invention versus lithium metal. Thestudy shows that the solid polymer electrolyte is stable up to about 4.4volts. These results indicate that the solid polymer electrolyte couldbe stable with cathodes including LCO, LMO, NMC and similar cathodes,along with low voltage cathodes such as, for non-limiting examples ironphosphate and sulfur cathodes.

The solid polymer electrolyte including the solid, ionically conductivepolymer material of the invention is able to achieve the followingproperties: A) high ionic conductivity at room temperature and over awide temperature range (at least −10° C. to +60° C.); B)non-flammability; C) extrudability into thin films allowing forreel-reel processing and a new way of manufacturing; D) compatibilitywith Lithium metal and other active materials. Accordingly, thisinvention allows for the fabrication of a true solid state battery. Theinvention allows for a new generation of batteries having the followingproperties:

-   -   No safety issues;    -   New form factors;    -   Large increases in energy density; and    -   large improvements in cost of energy storage.

FIGS. 11, 12 and 13 show several elements of the solid state batteryincluding the solid, ionically conductive polymer material of theinvention which are, respectively: A) an extruded electrolyte; B)extruded anodes and cathodes; and C) a final solid state batteryallowing for new form factors and flexibility.

In other aspects, the invention provides methods for making Li batteriesincluding the solid, ionically conducting polymer material of theinvention. FIG. 14 shows a method of manufacturing a solid state lithiumion battery using an extruded solid, ionically conducting polymermaterial according to the invention. The material is compounded intopellets, and then extruded through a die to make films of variablethicknesses. The electrodes can be applied to the film using severaltechniques, such as sputtering or conventional casting in a slurry.

In yet another aspect, the invention provides a method of manufacturingof an ionic polymer film including the solid, ionically conductivepolymer material of the invention which involves heating the film to atemperature around 295° C., and then casting the film onto a chill rollwhich solidies the plastic. This extrusion method is shown in FIG. 15.The resulting film can be very thin, in the range of 10 microns thick orless. FIG. 16 shows a schematic representation of the architecture of anembodiment according to the invention.

II. OH⁻ Chemistries

The invention also relates to a solid, ionically conducting polymermaterial which is engineered to transmit OH⁻ ions, thereby making itapplicable for alkaline batteries. For the purposes of presentinvention, the term “alkaline battery or alkaline batteries” refers to abattery or batteries utilizing alkaline (OH⁻ containing) electrolyte.Such battery chemistries include, but not limited to, Zn/MnO₂, Zn/Ni,Fe/Ni, Zn/air, Al/air, Ni/metal hydride, silver oxide and others.Zn/MnO₂ chemistry is probably the most widely used and is the mainchoice for consumer batteries. Although many of the embodimentsdescribed herein are related to Zn/MnO₂ chemistry, a person of ordinaryskill in the art would understand that the same principles areapplicable broadly to other alkaline systems.

Alkaline batteries rely on the transport of OH⁻ ions to conductelectricity. In most cases, the OH⁻ ion is also a participant in theelectrochemical process. For instance, during the discharge of a Zn/MnO₂battery, the zinc anode releases 2 electrons and consumes OH⁻ ions:Zn+4OH⁻→Zn(OH)₄ ²⁻+2e ⁻Zn+2OH⁻→Zn(OH)₂+2e ⁻→ZnO+H₂O  (1)Zn(OH)₂→ZnO+H₂O  (2)

During early stages of discharge of the battery, reaction (1) producessoluble zincate ions, which can be found in the separator and cathode[Linden's Handbook of Batteries, Fourth Edition]. At a certain point,the electrolyte will become saturated with zincates and the reactionproduct will change to insoluble Zn(OH)₂ (2). Eventually, the anode willbecome depleted of water and the zinc hydroxide dehydrates by equation(3). In rechargeable batteries, the reactions are reversed duringcharging of the battery. Formation of soluble zincate ions during theinitial step of the Zn discharge may hinder recharging.

The cathode reaction involves a reduction of Mn⁴⁺ to Mn³⁺ by a protoninsertion mechanism, resulting in the release of OFF ions (4). Thetheoretical specific MnO₂ capacity for such 1-electron reduction is 308mAh/g. Slow rate discharge to lower voltages may lead to furtherdischarge of MnOOH as depicted by equation (5), which results in 410mAh/g total specific capacity (1.33 e). In most prior art applications,the MnO₂ discharge is limited to the 1-electron process. Utilization ofthe active is further adversely affected by the formation of solublelow-valent Mn species.MnO₂ +e ⁻+H₂O→MnOOH+OH⁻3MnOOH+e ⁻→Mn₃O₄+H₂O+OH⁻  (3)MnO₂+2e ⁻+2H₂O→Mn(OH)₂+2 OH⁻  (4)

Although MnO₂ can theoretically experience a 2-electron reductionaccording to equation (6) with a theoretical specific capacity of 616mAh/g, in practice with prior art batteries, it is not demonstrated. Thecrystalline structure rearrangement with the formation of inactivephases, such as Hausmanite Mn₃O₄, and out-diffusion of soluble productsare among the factors limiting cathode capacity.

U.S. Pat. No. 7,972,726 describes the use of pentavalent bismuth metaloxides to enhance the overall discharge performance of alkaline cells.Cathode containing 10% AgBiO₃ and 90% electrolytic MnO₂ was shown todeliver 351 mAh/g to 0.8V cut-off at 10 mA/g discharge rate, compared to287 mAh/g for 100% MnO₂ and 200 mAh/g for 100% AgBiO₃. The 351 mAh/gspecific capacity corresponds to a 1.13 electron discharge of MnO₂ andrepresents the highest specific capacity delivered at practically usefuldischarge rates and voltage ranges.

In principle, reaction (4) can be reversible, opening the possibilityfor a rechargeable Zn/MnO₂ battery. In practice, the crystallinestructure collapse and formation of soluble products allow only forshallow cycling.

Bismuth- or lead-modified MnO₂ materials, disclosed in U.S. Pat. Nos.5,156,934 and 5,660,953, were claimed to be capable of delivering about80% of the theoretical 2-electron discharge capacity for many cycles. Itwas theorized in literature [Y. F. Yao, N. Gupta, H. S. Wroblowa, J.Electroanal. Chem., 223 (1987), 107; H. S. Wroblowa, N. Gupta, J.Electroanal. Chem., 238 (1987) 93; D. Y. Qu, L. Bai, C. G. Castledine,B. E. Conway, J. Electroanal. Chem., 365 (1994), 247] that bismuth orlead cations can stabilize crystalline structure of MnO₂ duringdischarge and/or allow for reaction (6) to proceed via heterogeneousmechanism involving soluble Mn²⁺ species. Containing said Mn²⁺ speciesseems to be the key for attaining high MnO₂ utilization andreversibility. In high carbon content (30-70%) cathodes per U.S. Pat.Nos. 5,156,934 and 5,660,953, the resulting highly porous structure wasable to absorb soluble species. However, there is no data to suggestthat a complete cell utilizing these cathodes was built or that thisworked using a Zn anode.

Thus, a polymer electrolyte which prevents dissolution and transport oflow-valent manganese species and zincate ions, would be highlybeneficial to improve MnO₂ utilization and achieve rechargeability ofZn/MnO₂ cells.

In addition to proton insertion, MnO₂ can undergo reduction by Liintercalation. It has been suggested [M. Minakshi, P. Singh, J. SolidState Electrochem, 16 (2012), 1487] that the Li insertion can stabilizeMnO₂ structure upon reduction and enable rechargeability.

The solid, ionically conductive polymer material of the invention,engineered to conduct Li+ and OH⁻ ions, opens the possibility to tuneMnO₂ discharge mechanism in favor of either proton or lithium insertion,which can serve as an additional tool to improve cycle life.

Accordingly, in one aspect, the invention provides a polymer materialincluding a base polymer, a dopant and at least one compound includingan ion source, wherein the polymer material is a solid, ionicallyconducting polymer material having mobility for OH⁻ ions. For thepurposes of the application, the term “mobility for OH⁻ ions” refers toa diffusivity of greater than 10⁻¹¹ cm²/sec or a conductivity of 10⁻⁴S/cm, at a room temperature of between 20° C. and 26° C. The solid,ionically conducting polymer material is suitable for use in alkalinecells.

In different aspects, the invention provides an electrolyte includingthe solid, ionically conductive polymer material having mobility for OH⁻ions, wherein the electrolyte is a solid polymer electrolyte for use inalkaline batteries; an electrode or electrodes including said solidpolymer electrolyte; and/or a cell or cells including said electrode orelectrodes.

In another aspect, the invention provides electrodes, cathodes andanodes including a solid polymer electrolyte for use in alkaline cells,wherein the solid polymer electrolyte includes a solid, ionicallyconducting polymer material having mobility for OH⁻ ions. In yet anotheraspect, the invention provides an electrolyte interposed between cathodeand anode, where at least one of the electrolyte, cathode and anodeincludes the solid, ionically conductive polymer material havingmobility for OH⁻ ions. In another aspect, the invention provides analkaline battery including a cathode layer, an electrolyte layer and ananode layer, wherein at least one of the layers includes a solid,ionically conducting polymer material having mobility for OH⁻ ions. Thelatter aspect is exemplarily illustrated in FIG. 17.

The base polymer of the solid, ionically conducting polymer materialhaving mobility for OH⁻ ions is a crystalline or semi-crystallinepolymer, which typically has a crystallinity value between 30% and 100%,and preferably between 50% and 100%. The base polymer of this aspect ofthe invention has a glass transition temperature above 80° C., andpreferably above 120° C., and more preferably above 150° C., and mostpreferably above 200° C. The base polymer has a melting temperature ofabove 250° C., and preferably above 280° C., and more preferably above280° C., and most preferably above 300° C.

The dopant of the solid, ionically conducting polymer material havingmobility for OH⁻ ions is an electron acceptor or oxidant. Typicaldopants for use in this aspect of the invention are DDQ, TCNE, SO₃, etc.

The compound including an ion source of the solid, ionically conductingpolymer material having mobility for OH⁻ ions includes a salt, ahydroxide, an oxide or other material containing hydroxyl ions orconvertible to such materials, including, but not limited to, LiOH,NaOH, KOH, Li₂O, LiNO₃, etc.

The solid, ionically conductive material having mobility for OH⁻ ions ischaracterized by a minimum conductivity of 1×10⁻⁴ S/cm at roomtemperature and/or a diffusivity of OH⁻ ions at room temperature ofgreater than 10⁻¹¹ cm²/sec.

The cathode of the present invention relating to OH⁻ chemistriesincludes MnO₂, NiOOH, AgO, air (O₂) or similar active materials. MnO₂ isa preferred material and can be in the form of β-MnO₂ (pyrolusite),ramsdellite, γ-MnO₂, ε-MnO₂, λ-MnO₂ and other MnO₂ phases or mixturesthereof, including, but not limited to, EMD and CMD.

The cathode of the present invention relating to OH⁻ chemistries isprepared by mixing cathode active material with the components of thesolid, ionically conducting polymer material of the invention includingthe base polymer, the dopant and a compound including a source of ionsprior to formation of the solid, ionically conducting polymer materialto form a mixture. Alternatively, the cathode active material is mixedwith the solid, ionically conducting polymer material already formed.

The mixture is molded and/or extruded at temperatures between 180° C.and 350° C., and preferably between 190° C. and 350° C., and morepreferably between 280° C. and 350° C., and most preferably between 290°C. and 325° C. The cathode active material can include various formssuch as, for non-limiting examples, a powder form, a particle form, afiber form, and/or a sheet form. The cathode of the present inventionincludes active material in an amount of between 10 w. % and 90 wt. %,and preferably in an amount of between 25 wt. % and 90 wt. %, and morepreferably in an amount of between 50 wt. % and 90 wt. %, relative tothe total cathode weight. The cathode can further include anelectrically conductive additive, such as a carbon black component, anatural graphite component, a synthetic graphite component, a graphenecomponent, a conductive polymer component, a metal particles component,and/or other like electrically conductive additives. The cathode caninclude the electrically conductive additives in an amount of between 0wt. % and 25 wt. %, and preferably in an amount of between 10 wt. % and15 wt. % relative to the total cathode weight. The cathode of thepresent invention relating to OH⁻ chemistries can further include one ormore functional additives for improving performance. The cathode activematerial can be encapsulated by the solid, ionically conducting polymermaterial of the invention.

The anode of the present invention relating to OH⁻ chemistries caninclude an active material of Zn, in the form of zinc powder, zincflakes and other shapes, zinc sheets, and other shapes. All such formsof zinc can be alloyed to minimize zinc corrosion.

The anode of the present invention relating to OH⁻ chemistries isprepared by mixing anode active material with the components of thesolid, ionically conducting polymer material of the invention includingthe base polymer, the dopant and a compound including a source of ionsprior to formation of the solid, ionically conducting polymer materialto form a mixture. Alternatively, the anode active material is mixedwith the solid, ionically conducting polymer material already formed.The mixture is molded and/or extruded at temperatures between 180° C.and 350° C. The anode of the present invention includes active materialin an amount of between 10 w. % and 90 wt. %, and preferably in anamount of between 25 wt. % and 90 wt. %, and more preferably in anamount of between 50 wt. % and 90 wt. %, relative to the total anodeweight. The anode can further include an electrically conductiveadditive, such as a carbon black component, a natural graphitecomponent, a synthetic graphite component, a graphene component, aconductive polymer component, a metal particles component, and/or otherlike electrically conductive additives. The anode can include theelectrically conductive additives in an amount of between 0 wt. % and 25wt. %, and preferably in an amount of between 10 wt. % and 15 wt. %relative to the total anode weight. The anode of the present inventionrelating to OH⁻ chemistries can further include one or more functionaladditives for improving performance. The anode active material can beencapsulated by the solid, ionically conducting polymer material of theinvention.

In another aspect, the invention provides a Zn/MnO₂ battery including anelectrolyte interposed between a MnO₂ cathode and a Zn anode. Theelectrolyte in this aspect can include the solid, ionically conductingmaterial of the invention having mobility for OH⁻ ions or can include atraditional separator filled with liquid electrolyte. The cathode caninclude the solid, ionically conducting material having mobility for OH⁻ions of the invention or can include a commercial MnO₂ cathode. Theanode in this aspect can include the solid, ionically conductingmaterial of the invention having mobility for OH⁻ ions or can include aZn foil, a Zn mesh or a Zn anode manufactured by other methods. In theZn/MnO₂ battery of the invention, the solid, electronically conductingpolymer material of the invention having mobility for OH⁻ ions isincluded in at least one of the cathode, the anode and the electrolyte.

III. Polymer-MnO₂ Composite Cathode

The invention further relates to a polymer-MnO₂ composite cathode with ahigh specific capacity and a primary alkaline cell including thecathode. More specifically, the invention further relates to apolymer-MnO₂ composite cathode with a specific capacity close totheoretical 2-electron discharge and a primary alkaline cell comprisingthe cathode. The alkaline cell can be discharged at current densitiescomparable to that of commercial alkaline cells, while useful capacityis delivered to typical 0.8V voltage cut-off.

In different aspects, the invention features a cathode that is made of aMnO₂ active material including a plurality of active MnO₂ particlesintermixed with a solid, ionically conductive polymer material includinga base polymer, a dopant, and a compound including an ion source and amethod of making said cathode. In other aspects, the invention featuresan electrochemical cell including a cathode, an anode and a separatordisposed between the cathode and the anode, and a method for making saidcathode. The cathode is made of a MnO₂ active material including aplurality of active MnO₂ particles intermixed with a solid, ionicallyconductive polymer material including a base polymer, a dopant, and acompound including an ion source. The cathode and the electrochemicalcell of the present invention are characterized by flat dischargecurves.

In the aspects of the invention related to the polymer-MnO₂ compositecathode, the base polymer can be a semicrystalline polymer. The basepolymer can be selected from a group which consists of a conjugatedpolymer or a polymer which can easily be oxidized. Non-limiting examplesof the base polymers used in this aspect of the invention include PPS,PPO, PEEK, PPA, etc.

In the aspects of the invention related to the polymer-MnO₂ compositecathode, the dopant is an electron acceptor or oxidant. Non-limitingexamples of dopants are DDQ, tetracyanoethylene also known as TCNE, SO₃,ozone, transition metal oxides, including MnO₂, or any suitable electronacceptor, etc.

In the aspects of the invention related to the polymer-MnO₂ compositecathode, the compound including the ion source is a salt, a hydroxide,an oxide or other material containing hydroxyl ions or convertible tosuch materials, including, but not limited to, LiOH, NaOH, KOH, Li₂O,LiNO₃, etc.

In the aspects of the invention related to the polymer-MnO₂ compositecathode, the MnO₂ active material can be in the form of β-MnO₂(pyrolusite), ramsdellite, γ-MnO₂, ε-MnO₂, λ-MnO₂ and other MnO₂ phasesor mixtures thereof, including, but not limited to, EMD and CMD.

The cathode related to the polymer-MnO₂ composite cathode can be madeprepared by mixing a plurality of active MnO₂ particles and a solid,ionically conducting polymer material including a base polymer, a dopantand a compound including an ion source, and heating the mixture to aspecific temperature for a specific time. Said heating can optionally beperformed while applying pressure.

In one embodiment, the polymer-MnO₂ composite cathode of the presentinvention can be prepared by compression molding at a temperature ofbetween The mixture is molded and/or extruded at temperatures between180 and 350° C., and preferably between 190° C. and 350° C., and morepreferably between 280° C. and 350° C., and most preferably between 290°C. and 325° C. In other embodiments, the heating is optionally conductedat a pressure of between 150-2000 PSI, and preferably between 150-1000PSI and more preferably between 150-500 PSI, and most preferably between150-250 PSI. The MnO₂ active material can be in an amount of between 5wt. % and 95 wt. % and preferably between 50 wt. % and 90 wt. % relativeto the total weight of the composite cathode. The composite cathode caninclude a filler in the amount of between 5 wt. % and 50 wt. %, andpreferably between 10 wt. % and 50 wt. %, and more preferably between 20wt. % and 40 wt. %, and most preferably between 25 wt. % and 35 wt. %relative to the total weight of the composite cathode. The dopant can beadded in the amount corresponding to a base polymer/dopant molar ratiobetween 2 and 10, and preferably between 2 and 8, and more preferablybetween 2 and 6, and most preferably between 3 and 5. The compositecathode can include an electrically conductive additive, such as acarbon black component, a natural and/or a synthetic graphite component,a graphene component, an electrically conductive polymer component, ametal particles component, and another component, wherein theelectrically conductive component is in the amount of between 5 wt. %and 25 wt. %, and preferably between 15 wt. % and 25 wt. %, and morepreferably between 18 wt. % and 22 wt. % relative to the total weight ofthe composite cathode. The MnO₂ active material in the composite cathodecan be encapsulated by solid, ionically conducting polymer material ofthe invention.

In a preferred embodiment, the invention features an alkaline batteryincluding said polymer-MnO₂ composite cathode and a Zn anode. The Znanode can be in the form of slurry including Zn or Zn alloy powder, KOH,gelling agent and optionally other additives. The Zn anode can furtherinclude an electrically conductive additive, similar to the compositecathode.

The anode related to the polymer-MnO₂ composite of the invention caninclude Zn, Al, Fe, metal hydride alloys or similar materials. Zn and Alare preferred materials and can be in the form of pure metals orspecially designed alloys. The separator can be a traditional non-wovenseparator used in alkaline batteries. Electrolyte is KOH, NaOH, LiOHetc. solution in water. Alkali concentration can be between 4 and 9 M.The Electrolyte can further contain an electronically conductiveadditive and/or a functional additive.

III. Polymer-Sulfur Cathode

In addition, the invention relates to a composite polymer-sulfurcathode. The composite polymer-sulfur cathode includes a sulfurcomponent and a solid, ionically conducting polymer material including abase polymer, a dopant and a compound including a source of ions. Thecomposite polymer-sulfur cathode is characterized as having a highspecific capacity and a high capacity retention when employed in asecondary lithium or Li-ion sulfur cell. The composite cathode ischaracterized as having a specific capacity of greater than 200milliamp-hr/gm, and preferably greater than 500 milliamp-hr/gm, and morepreferably greater than 750 milliamp-hr/gm, and most preferably greaterthan 1000 milliamp-hr/gm. The composite cathode is characterized ashaving a retention of least 50% and preferably at least 80% for over 500recharge/discharge cycles. The composite polymer-sulfur cathode of thepresent invention has direct application to low-cost, large-scalemanufacturing enabled by the unique polymer used in this compositeelectrode. The composite polymer-sulfur cathode of the invention canprovide high performance while simultaneously meeting the requirementsfor producing low-cost batteries.

Notably, sulfur cathodes reduce during discharge to create sequentiallylower order polysulfides through the sequence illustrated in thefollowing equation:S₈→Li₂S₈→Li₂S₄→Li₂S₂→Li₂S

The intermediate polysulfides between Li₂S₈ and Li₂S₄ are soluble inliquid electrolytes. Thus, dissolved polysulfide particles are able tomigrate (or “shuttle”) across porous separators and react directly withthe anode and cathode during cycling. The polysulfide shuttle producesparasitic reactions with the lithium anode and re-oxidation at thecathode, all causing capacity loss. Furthermore, aspects of this shuttlereaction are irreversible, leading to self-discharge and low cycle lifethat has, until now, plagued lithium sulfur batteries.

The present invention demonstrates a composite polymer-sulfur cathodeincluding a sulfur component and a solid, ionically conducting polymermaterial. This cathode can be extruded into a flexible, thin film via aroll-to-roll process. Such thin films enable thin, flexible form factorswhich can be incorporated into novel flexible battery designs. As shownin the examples which follow, this composite polymer-sulfur cathode caninclude an electrically conductive addition such as, for example, aninexpensive carbon black component, such as Timcal C45, which is alreadyin use for many commercial battery products. In addition to theexemplary carbon black component, the composite polymer-sulfur cathodecan include other electrically conductive additives such as, fornon-limiting examples, a carbon component including but not limited tocarbon fibers, a graphene component, a graphite component, metallicparticles or other metal additives, and an electrically conductivepolymer.

The engineering properties of the composite polymer-sulfur cathode allowthe extrusion of the cathode into a wide range of possible thicknesses,which in turn provides important advantages in terms of flexibility indesign in large-scale cathode manufacturing. The compositepolymer-sulfur cathode can be extruded as thin as 5 microns and up tothicknesses greater than several 100 microns.

A comparison of the process steps necessary for producing standardlithium ion cathodes with those necessary to produce the inventivecomposite polymer-sulfur cathode is instructive relative to the inherentlower cost of the composite polymer-sulfur cathode manufacturing. FIG.18 illustrates the process steps needed to manufacture a standardlithium ion cathode compared with the much simpler manufacturing of anextruded composite polymer-sulfur cathode of the invention. Theextrusion process for the composite polymer-sulfur cathode is easilyscaled-up to high volume manufacturing which provides a significantadvantage over existing lithium ion battery, as well as a much lowercapital expenditure for factory equipment.

In addition to extrusion, the composite polymer-sulfur cathode can beformed by injection molding, compression molding, or any other processinvolving heat, or other techniques known by those skilled in the artfor engineering plastics.

The composite polymer-sulfur cathode includes a sulfur component and asolid, ionically conducting polymer material including a base polymer, adopant and a compound including a source of ions, as discussed above.

The base polymer includes liquid crystal polymers and polyphenylenesulfide (PPS), or any semicrystalline polymer with a crystallinity indexgreater than 30%, or other typical oxygen acceptors.

The dopant includes electron acceptors which activate the ionicconduction mechanism. These electron acceptors can be pre-mixed alongwith the other ingredients, or supplied in the vapor phase as a postdoping process. Typical electron acceptor dopants suitable for useinclude, but are not limited to:2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) (C₈Cl₂N₂O₂),Tetracyanoethylene (TCNE) (C₆N₄), and sulfur trioxide (SO₃).

The compounds including an ion source include, but are not limited toLi₂O and LiOH. Use of composite polymer-sulfur cathodes in Li/Sulfurtest cells has shown that the composite polymer-stable cathodes arestable to lithium, sulfur, and organic electrolytes typically used inlithium/sulfur batteries.

The base polymer is a nonflammable polymer which has been shown toself-extinguish and pass the UL-VO Flammability test. Thenon-flammability of the base polymer is a safety benefit to batteriesemploying the composite polymer-sulfur cathode. The incorporation of thenon-flammable composite polymer-sulfur cathode into a cell withnon-flammable electrolyte will further improve the safety of thebattery, an important attribute for high energy density batteries.

The sulfur component can include non-reduced and/or reduced forms ofsulfur including elemental sulfur. In particular, the compositepolymer-sulfur cathode includes a sulfur component including the fullylithiated form of sulfur (Li₂S), wherein the Li₂S, is a solid. Thecomposite polymer-sulfur cathode can also include a carbon component.The advantage to using the fully lithiated form of sulfur is that itprovides a lithium source for a sulfur battery with a Li Ion anode,which, unlike metal Li, must by lithiated during initial charge.Combination of a sulfur cathode with a Li-ion anode provides benefit inpreventing the formation of lithium dendrites which can be formed aftercycling lithium anodes. Dendrites are caused by a non-uniform plating oflithium onto the lithium metal anode during charging. These dendritescan grow through separator materials and cause internal short circuitsbetween cathode and anode, often leading to high temperatures andcompromised safety of the battery. Materials that reversibly incorporatelithium, either through intercalation or alloying, lessen the chance fordendrite formation and have been proposed for use in high safetylithium/sulfur cells. The composite polymer-sulfur cathode can be usedwith an anode material such as, for example, a carbon-based (petroleumcoke, amorphous carbon, graphite, carbon nano tubes, graphene, etc.)material, Sn, SnO, SnO₂ and Sn-based composite oxides, includingcomposites with transition metals, such as Co, Cu, Fe, Mn, Ni, etc.Furthermore, silicon has shown promise as a lithium ion anode material,in the elemental form, or as an oxide or composite material, asdescribed for tin. Other lithium alloying materials (for example, Ge,Pb, B, etc.) could also be used for this purpose. Oxides of iron, suchas Fe₂O₃ or Fe₃O₄ and various vanadium oxide materials have also beenshown to reversibly incorporate lithium as a Li-ion anode material.Anode materials may be considered in different forms, includingamorphous and crystalline, and nano-sized particles as well asnano-tubes.

The composite polymer-sulfur cathode can be combined with a standardliquid electrolyte, a standard nonwoven separator, and/or an electrolyteincluding a solid, ionically conducting polymer material with no liquidelectrolyte. An example of a standard organic electrolyte solutionincludes a lithium salt, such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), dissolved in a mixture of 1,3-dioxolane (DOL)and 1,2-dimethoxyethane (DME). Additives, such as LiNO₃, can be added tothe electrolyte to improve cell performance. Other lithium salts can beutilized in organic liquid electrolyte, including: LiPF₆, LiBF₄, LiAsF₆,lithium triflate, among others. Additionally, other organic solvents canbe used, such as propylene carbonate (PC), ethylene carbonate (EC),diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methylcarbonate (EMC), fluoroethylene carbonate (FEC), as a few examples,either alone or as mixtures together or with DOL and DME. Examples ofstandard nonwoven separators include polypropylene (PP), polyethylene(PE), and combinations of PP/PE films. Other separator materials includepolyimide, PTFE, ceramic coated films and glass-mat separators. All ofthe above materials can be used with the composite polymer-sulfurcathode. Further, the composite polymer-sulfur cathode could also beutilized in a gel-polymer system, where for example, a PVDF-basedpolymer is swelled with an organic electrolyte.

It is believed that the ability of the composite polymer-sulfur cathodeto provide lithium ionic conductivity improves the performance of thecell by limiting the polysulfide shuttle mechanism, while simultaneouslyproviding a sulfur cathode with high voltage. Furthermore, this uniqueengineering composite polymer-sulfur cathode allows for the large scale,low cost manufacturing necessary for commercial viability of thecathode.

Thus, the unique composite polymer-sulfur cathode has numerous potentialbenefits to batteries, including:

-   -   Improved safety, under normal and abuse conditions    -   Enabling new battery form factors    -   Large increase in energy density over existing Li-ion cells    -   Prevention of the polysulfide shuttle mechanism, leading to        greater charge/discharge reversibility    -   Large decrease in manufacturing cost (raw materials, process and        capital equipment) leading to improvement in the cost of energy        storage

Example 1

Solid polymer electrolyte was made by mixing PPS base polymer and ionsource compound LiOH monohydrate in the proportion of 67% to 33% (bywt.), respectively, and mixed using jet milling. DDQ dopant was added tothe resulting mixture in the amount of 1 mole of DDQ per 4.2 moles ofPPS. The mixture was heat treated at 325/250° C. for 30 minutes undermoderate pressure (500-1000 PSI). After cooling, the resulting materialwas grinded and placed into NMR fixture.

Self-diffusion coefficients were determined by using pulsed fieldgradient solid state NMR technique. The results shown in FIGS. 19 and 20indicate, respectively, that Li⁺ and OFF diffusivity in the solidpolymer electrolyte is the highest of any known solid, and over an orderof magnitude higher at room temperature compared to recently developedLi₁₀GeP₂S₁₂ ceramic at much higher temperatures (140° C.) or the bestPEO formulation at 90° C.

Example 2

PPS base polymer and ion source compound LiOH monohydrate were addedtogether in the proportion of 67% to 33% (by wt.), respectively, andmixed using jet milling. Cathode was prepared by additionally mixing50%β-MnO₂ form Alfa Aesar, 5% of Bi₂O₃ and 15% of C45 carbon black. DDQdopant was added to the resulting mixture in the amount of 1 mole of DDQper 4.2 moles of PPS.

The mixture was compression molded onto stainless steel mesh (Dexmet) at325/250° C. for 30 minutes under moderate pressure (500-1000 PSI),yielding cathode disc 1 inch in diameter and about 0.15 mm thick. Theresulting disc was punched to 19 mm diameter and used as a cathode toassemble test cells, containing commercial non-woven separator (NKK) andZn foils anode. 6M LiOH was added as electrolyte.

Cells were discharged under constant current conditions of 0.5 mA/cm²using Biologic VSP test system. The specific capacity of MnO₂ was 303mAh/g or close to theoretical 1e⁻ discharge. FIG. 21 illustrates thevoltage profile of the cell per Example 2 as a function of specificcapacity of MnO₂ at 0.5 mA/cm² discharge rate.

Example 3

PPS base polymer and ion source compound LiOH monohydrate were addedtogether in the proportion of 67% to 33% (by wt.), respectively, andmixed using jet milling. Cathode was prepared by additionally mixing 50%β-MnO₂ form Alfa Aesar, 5% of Bi₂O₃ and 15% of C45 carbon black. DDQdopant was added to the resulting mixture in the amount of 1 mole of DDQper 4.2 moles of PPS.

The mixture was compression molded onto stainless steel mesh (Dexmet) at325/250 C for 30 minutes under moderate pressure (500-1000 psi),yielding cathode disc 1″ in diameter and 1.6-1.8 mm thick.

The resulting cathodes were used to assemble test cells, containingcommercial non-woven separator (NKK) and Zn anode slurry extracted fromcommercial alkaline cells. 6M KOH solution in water was used aselectrolyte.

Cells were discharged under constant current conditions using BiologicVSP test system. The specific capacity of MnO₂ was close to 600 mAh/g atC/9 discharge rate (35 mA/g), or close to theoretical 2 e⁻ discharge.

FIG. 22 shows the voltage profile of the cell per Example 3 as afunction of specific capacity of MnO₂ at C/9 rate (35 mA/g).

Example 4

PPS base polymer and ion source compound LiOH monohydrate were addedtogether in the proportion of 67% to 33% (by wt.), respectively, andmixed using jet milling. Cathode was prepared by additionally mixing 50%β-MnO₂ form Alfa Aesar, 5% of Bi₂O₃ and 15% of C45 carbon black. DDQdopant was added to the resulting mixture in the amount of 1 mole of DDQper 4.2 moles of PPS.

The mixture was compression molded onto stainless steel mesh (Dexmet) at325/250° C. for 30 minutes under moderate pressure (500-1000 PSI),yielding cathode disc 1 inch in diameter and about 0.15 mm thick.

The resulting disc was punched to 19 mm diameter and used as a cathodeto assemble test cells, containing commercial non-woven separator (NKK)and Zn foil anode. 6M LiOH was added as electrolyte.

The cells were discharged and charged using a Biologic VSP test system.Discharge was conducted at 0.5 mA/cm² current to 0.8 V cut-off. Chargewas performed at 0.25 mA/cm² to 1.65 V, then held at 1.65V for 3 hoursor until current declined to 0.02 mA/cm². Every few cycles passivated Znanode and separator were replaced with fresh. Specific capacity of MnO₂as a function of cycle number in cells per Example 4 is plotted at FIG.23. Each column represents separate cell. Only discharges with fresh Znanode are shown. It is easy to see that MnO₂ cathode of presentinvention is rechargeable. Only discharges with fresh Zn anode areshown.

Example 5

A 2035 coin cell was assembled using the solid polymer electrolyte ofExample 1, the cathode of Example 2 and a Zn foil as anode. The cell wasdischarged and charged using a Biologic VSP test system. Discharge wasconducted at 0.25 mA/cm² current to 0.8 V cut-off. Charge was performedat 0.25 mA/cm² to 1.65 V, then held at 1.65V for 3 hours or untilcurrent declined to 0.02 mA/cm². The cell demonstrated reversiblebehavior during such cycling. FIG. 24 shows the discharge curve of thecoin cell per Example 5 as a function of test time.

Example 6

PPS base polymer and ion source compound LiOH monohydrate were addedtogether in the proportion of 67% to 33% (by wt.), respectively, andmixed using jet milling. Cathode was prepared by additionally mixing 55%β-MnO₂ form Alfa Aesar and 15% of C45 carbon black. DDQ dopant was addedto the resulting mixture in the amount of 1 mole of DDQ per 4.2 moles ofPPS.

The mixture was compression molded onto stainless steel mesh (Dexmet) at325/250 C for 30 minutes under moderate pressure (500-1000 psi),yielding cathode disc 1 inch in diameter and about 0.15 mm thick.

The test cell was assembled using the resulting cathode, electrolyte perExample 1 and anode made of Zn powder. The cell was discharged usingBiologic VSP test system at 0.5 mA/cm² current density to 0.8 V cut-off.Specific capacity of MnO₂ was 401 mAh/g or more than theoretical1-electron discharge. FIG. 25 shows the voltage profile of the cell perExample 6 as a function of test time.

Example 7

PPS base polymer and ion source compound LiOH monohydrate were addedtogether in the proportion of 67% to 33% (by wt.), respectively, andmixed using jet milling. Anode was prepared by additionally mixing 60%of Zn powder and 10% of C45 carbon black. DDQ dopant was added to theresulting mixture in the amount of 1 mole of DDQ per 4.2 moles of PPS.

The mixture was compression molded onto stainless steel mesh (Dexmet) at325/250 C for 30 minutes under moderate pressure (500-1000 psi),yielding cathode disc 1″ in diameter and about 0.15 mm thick.

The 2035 coin cell was assembled using the resulting anode, cathode perexample 2 and commercial NKK separator, containing saturated LiOH aselectrolyte.

The control coin cell was made using Zn foil as anode, cathode perExample 2 and commercial NKK separator containing saturated LiOH aselectrolyte.

The cells were discharged using a Biologic VSP test system at 0.5 mA/cm²current density. The discharge profile with anode of the presentinvention shows higher capacity at slightly higher voltage, which can berelated to increased surface area of Zn anode and retention of solublezincates inside the anode structure. FIG. 26 shows the discharge curveof coin cells per Example 7 as a function of discharge capacity.Discharge was conducted at 0.25 mA/cm² current to 0.7 V cut-off. CurveA—cell with anode of the present invention. Curve B—cell with Zn foilanode. FIG. 26 shows the discharge curve of coin cells per Example 7 asa function of discharge capacity. Discharge was conducted at 0.25 mA/cm²current to 0.7 V cut-off. Curve A—cell with anode of the presentinvention. Curve B—cell with Zn foil anode.

Example 8

PPS base polymer and an ion source compound LiOH monohydrate were addedtogether in the proportion of 67% to 33% (by wt.), respectively, andmixed using jet milling. Anode was prepared by additionally mixing 60%of Al powder and 10% of C45 carbon black. DDQ dopant was added to theresulting mixture in the amount of 1 mole of DDQ per 4.2 moles of PPS.

The mixture was compression molded onto stainless steel mesh (Dexmet) at325/250 C for 30 minutes under moderate pressure (500-1000 psi),yielding cathode disc 1″ in diameter and about 0.15 mm thick.

The resulting anode was tested in test cell containing Zn counterelectrode and commercial separator containing ZnSO4 electrolyte. Anodemade of Al foil was tested as a control.

The anode was polarized potentiodynamically at 1 mV/s sweep rate usingBiologic VSP test system. FIG. 27 shows a potentiodynamic scan at 1 mV/sof anode of the present invention (curve A) and control Al foil (curveB) in ZnSO4 electrolyte. Anode of the present invention demonstratedcorrosion stability improved by 0.5 V compared to Al foil.

Comparative Example 9

Discharge profile of Duracell Coppertop AA cell at 250 mA discharge wastaken from the datasheet. Amount of MnO₂ in the cell was calculated bycomparison of published specifications and MSDS, yielding between 8.4and 9.6 g. Simple conversion results in current density between 26 and30 mA/g. Product of service hours (per datasheet) and discharge currentyields total capacity, which can be converted to specific capacity bydividing it by weight of MnO₂. Voltage profile of the Coppertop AA cellas a function of specific MnO₂ capacity, calculated in such manner, isshown at FIG. 28. Curve A corresponds to maximum amount MnO₂ (9.6 g)where specific capacity of Duracell Coppertop AA cell is under constantcurrent discharge at 26 mA/g rate. Curve B corresponds to minimum amountof MnO₂ (8.4 g) where specific capacity of Duracell Coppertop AA cellunder constant current discharge is at 30 mA/g rate. Curve C shows aspecific capacity of Duracell Coppertop AA cell under a constant currentdischarge rate of 2.2 mA/g. It is easy to see that MnO₂ specificcapacity, calculated to 0.9 V cut-off, is between 235 and 270 mAh/g.Extrapolation to 0.8 V cut-off will result in slightly better specificcapacity between 245 and 275 mAh/g. Discharge curves have typicalsloping shape, characteristic to Zn/MnO₂ cells. Difference betweenvoltage at 5% depth of discharge and 95% depth of discharge is close to0.5 V or 30% of initial (5% DOD) [2.1-2.4 V/Ah/g]. Discharging Coppertopcell at extremely low rate of 2.2 mA/g (assuming average amount of MnO₂in the cell) results in appearance of additional plateau (curve C).Total specific capacity was 347 mA/g, corresponding to 1.13-electrondischarge. The discharge curve still has typical slopping shape withclose to 0.5 V voltage difference between 5 and 95% depth of discharge.

Comparative Example 10

AA cells were purchased in retail store and subjected to 250 mAdischarge, corresponding to mid-rate test, using a Maccor 4300 system.Table 10.1 shows performance of commercial AA cells under 250 mAcontinuous discharge. Total capacity delivered to 0.9 V cut-off is shownin Table 10.1. Assuming amount of MnO₂ in the cells is the same asComparative example 9, the total capacity of the cell can be convertedto specific capacity of MnO₂. As one can see, under these dischargeconditions commercial AA cells deliver between 200 and 280 mAh/g. Eventaking into account positive effect of intermittent discharge andextending voltage cut-off to 0.8V, it is a fare statement thatcommercial alkaline cells operate within 1-electron reduction of MnO₂,described by equation (1), and are limited to 308 mAh/g.

TABLE 10.1 Total Capacity Specific Capacity (mAh/g) Cell Ah Min MaxRayovac 2.15 224 256 Rayovac 2.11 220 251 Energizer Max 1.84 191 219Energizer Max 1.82 190 217 Duracell Coppertop 2.15 224 256 DuracellCoppertop 2.13 222 254 Duracell Quantum 2.35 244 279 Duracell Quantum2.33 243 277

Comparative Example 11 Per U.S. Pat. No. 7,972,726

FIG. 29 shows discharge curves for alkaline button cells with cathodesbased on AgBiO₃ cathode (curve (a)), EMD (MnO₂) cathode (curve (b)) and1:9 AgBiO₃:EMD mixture at 10 mA/g discharge rate (curve (c)), reproducedfrom U.S. Pat. No. 7,972,726. Under these conditions, discharge profilefor EMD (b) is similar to commercial alkaline cell described incomparative example 9 with 0.5 V difference between voltage at 5 and 95%DOD. MnO₂ capacity of about 290 mAh/g is consistent with 1-electrondischarge. Cathodes made with AgBiO₃:EMD mixture displayed additionalplateau at about 0.9 V, boosting MnO₂ capacity. Best performance wasreported with 1:9 AgBiO₃:EMD mixture, which delivered 351 mAh/g before0.8 V cut-off. This corresponds to 1.13-electron discharge of MnO₂.

Example 12

PPS base polymer and ion source compound LiOH monohydrate were addedtogether in the proportion of 67% to 33% (by wt.), respectively, andmixed using jet milling. Cathode was prepared by additionally mixing 50%β-MnO₂ from Alfa Aesar, 5% of Bi₂O₃ and 15% of C45 carbon black. DDQdopant was added to the resulting mixture in the amount of 1 mole of DDQper 4.2 moles of PPS.

The mixture was compression molded onto stainless steel mesh (Dexmet) at325/250 C for 30 minutes under moderate pressure (500-1000 psi),yielding cathode disc 1″ in diameter and 1.6-1.8 mm thick.

The resulting cathodes were used to assemble test cells, containingcommercial non-woven separator (NKK) and Zn anode slurry extracted fromcommercial alkaline cells. 6M KOH solution in water was used aselectrolyte.

Cell was discharged under constant current conditions using Biologic VSPtest system. FIG. 30 shows the voltage profile of cell per Example 12 at35 mA/g constant current discharge as a function of specific capacity ofMnO₂. The discharge profile, shown at FIG. 30, looks significantly moreflat, compared to conventional Zn/MnO₂ cells. Voltage difference between5 and 95% DOD is about 0.1 V or less than 10% of initial. The specificcapacity of MnO₂ was close to 600 mAh/g or 97% of theoretical 2-electrondischarge (616 mAh/g).

Example 13

PPS base polymer and ion source compound LiOH monohydrate were addedtogether in the proportion of 67% to 33% (by wt.), respectively, andmixed using jet milling. Cathode was prepared by additionally mixing 50%EMD from Tronox (mixture of γ- and ε-MnO₂), 5% of Bi2O3 and 15% of C45carbon black. DDQ dopant was added to the resulting mixture in theamount of 1 mole of DDQ per 4.2 moles of PPS.

The mixture was compression molded onto stainless steel mesh (Dexmet) at325/250 C for 30 minutes under moderate pressure (500-1000 psi),yielding cathode disc inch in diameter and 1.6-1.8 mm thick.

The resulting cathodes were used to assemble test cells, containingcommercial non-woven separator (NKK) and Zn anode slurry extracted fromcommercial alkaline cells. 6M KOH solution in water was used aselectrolyte.

Cells were discharged under constant current conditions using BiologicVSP test system. FIG. 31 shows the voltage profile of the cell perExample 13 as a function of specific capacity of MnO₂ at 29 mA/g (CurveA) and 59 mA/g (Curve B). The specific capacity of MnO₂ was close to 600mAh/g at 29 mA/g rate and close to 560 mAh/g at 59 mA/g rate.

Example 14

PPS base polymer and ion source compound LiOH monohydrate were addedtogether in the proportion of 67% to 33% (by wt.), respectively, andmixed using jet milling. Cathode was prepared by additionally mixing 80%EMD from Tronox (mixture of γ- and ε-MnO₂), 5% of C45 carbon black. DDQdopant was added to the resulting mixture in the amount of 1 mole of DDQper 4.2 moles of PPS.

The mixture was compression molded onto stainless steel mesh (Dexmet) at325/250 C for 30 minutes under moderate pressure (500-1000 psi),yielding cathode disc 1″ in diameter and 1.6-1.8 mm thick.

The resulting cathodes were used to assemble test cells, containingcommercial non-woven separator (NKK) and Zn anode slurry extracted fromcommercial alkaline cells. 7M KOH solution in water was used aselectrolyte.

The cell was discharged under constant current conditions at a rate of 9mA/g using Biologic VSP test system. The specific capacity of MnO₂ was590 mAh/g. FIG. 32 shows the voltage profile of cell per Example 14 as afunction of specific capacity of MnO₂ at 9 mA/g discharge rate (curve A)and Duracell Coppertop cells at 2.2 mA/g (curve B). The voltagedifference between 5 and 95% DOD was 0.163V or 13.6% (Curve A).Discharge profile for Duracell Coppertop cell at 2.2 mA/g is shown forcomparison (Curve B).

Example 15

PPS base polymer and ion source compound LiOH monohydrate were addedtogether in the proportion of 67% to 33% (by wt.), respectively, andmixed using jet milling. Cathode was prepared by additionally mixing 80%EMD from Erachem (mixture of γ- and ε-MnO₂), 5% of C45 carbon black. DDQdopant was added to the resulting mixture in the amount of 1 mole of DDQper 4.2 moles of PPS.

The mixture was compression molded onto stainless steel mesh (Dexmet) at325/250 C for 30 minutes under moderate pressure (500-1000 psi),yielding cathode disc 1″ in diameter and 1.6-1.8 mm thick.

The resulting cathodes were used to assemble test cells, containingcommercial non-woven separator (NKK) and Zn anode slurry extracted fromcommercial alkaline cells. 7M KOH solution in water was used aselectrolyte.

The cell was discharged under constant current conditions at a rate of9.5 mA/g using Biologic VSP test system. The specific capacity of MnO₂was 541 mAh/g. FIG. 33 shows the voltage difference between 5 and 95%DOD was 0.180V or 14.1% (Curve A). Discharge profile for DuracellCoppertop cell at 2.2 mA/g is shown for comparison (Curve B).

Example 16

PPS base polymer and ion source compound LiOH monohydrate were addedtogether in the proportion of 67% to 33% (wt/wt), respectively, and weremixed using jet milling. The mixture was compression molded at 325°C./250° C. for 30 minutes under low pressure. The polymer-sulfurcomposite cathode was prepared by additionally mixing from 25% to 50% ofsulfur powder, 5% to 15% of C45 carbon black, and 0% to 10% LiNO₃ withthe solid, ionically conducting polymer material. The materials werecompression molded onto stainless steel mesh (Dexmet) at 120° C. for 30minutes, yielding a cathode disc 15 mm in diameter and 0.3 to 0.4 mmthick.

The resulting cathodes were used to assemble test cells in 2035 coincell hardware. Polypropylene separator (Celgard) 25 microns thick and 19mm in diameter was used along with lithium foil anode material, 15 mm indiameter. A liquid electrolyte of 1M LiTFSI salt dissolved in a 50/50(vol/vol) mixture of DOL/DME was used, with 0.5M LiNO₃ additive. Thecells were assembled in an argon gas filled glovebox, with low oxygenand water levels.

Cells were discharged under constant current conditions (1 mA) using aMaccor 4600 battery test system. Discharge was terminated at a voltageof 1.75 V.

FIG. 34 shows a first discharge voltage curve for a Li/compositepolymer-sulfur cathode in a cell of the present invention. The dischargevoltage profile for the first cycle is displayed in FIG. 34. It can beseen that the composite polymer-sulfur cathode provides a high initialcapacity of >1300 mAh/g, based on the amount of sulfur in the cathode.The cell in FIG. 34 also displays a discharge voltage curve with twoplateaus, at ˜2.3V and ˜2.1V. This shows that the compositepolymer-sulfur system enables high capacity, while producing theexpected voltage curve for a lithium/sulfur system, consistent with astable electrochemical couple.

Example 17

Composite polymer-sulfur cathodes were manufactured as described inExample 16. These cathodes were assembled into coin cells using lithiummetal anodes, polypropylene separator, and 1M LiTFSI in DOL/DMEelectrolyte with 0.5M LiNO₃ additive.

Cells were discharged under constant current conditions (1 mA) using aMaccor 4600 battery test system. Discharge was terminated at a voltageof 1.75 V. Charge was accomplished in two steps, the first at a lowercharge rate of 0.2 mA current to a maximum voltage of 2.3 V, and thesecond charge step at a higher rate of 1 mA current to a maximum voltageof 2.45 V. The overall charge capacity was limited for these test cells.These cells were allowed to cycle several times at room temperature.

FIG. 35 shows the discharge capacity curve plotted as a function ofcycle number for Li/composite polymer-sulfur cell of the presentinvention. This graph shows that the composite polymer-sulfur cathodewill support reversible charge/discharge, with high reversible capacityof at least 1000 mAh/g based on the amount of sulfur in the cathode.

Comparative Example 18

A noteworthy example of a highly ordered interwoven composite electrodeis presented in the literature [Ji, X.; Lee, K. T.; Nazar, L. F. NatureMaterials 2009, 8, 500-506]. This composite cathode utilized CMK-3mesoporous carbon with sulfur entrenched in the pores through heattreatment at 155° C. FIG. 36 compares the first discharge for literatureexample Li/Sulfur-CMK-3 with Li/composite polymer-sulfur of presentinvention.

The composite cathode in this example was slurry-cast fromcyclopentanone onto a carbon coated aluminum current collector. Thecathode utilized 84 wt % CMK-3/S composite, 8 wt % Super-S carbon and 8wt % PVDF binder. The electrolyte was composed of 1.2 M LiPF₆ in ethylmethyl sulphone, and Li metal was used as the anode. In comparison, theresults for the composite polymer-sulfur cathode of the invention, asdescribed in Example 16, are plotted on the same graph. It is apparentthat the composite polymer-sulfur cathode of the invention gives asgood, or better, results than literature examples of composite sulfurcathodes.

Comparative Example 19

The use of sulfur-conductive polymer composites as cathodes for lithiumbatteries has been demonstrated. In one case, polyacrylonitrile (PAN) issulfurized to form a conductive and chemically active cathode material.The sulfurization of the polymer takes place at a relatively hightemperature of ˜300° C. An example of the discharge curve for thismaterial is shown in FIG. 37, which was displayed in U.S. PatentApplication 2014/0045059 [He, X.-M., et. al.]. FIG. 37 shows the typicalvoltage signature seen for Li/Sulfur-Polyacrylonitrile (S/PAN) cells.These cells are typified by a single sloping voltage plateau, with anaverage voltage below 2.0 V. In comparison to the voltage curve observedin FIG. 4 for the Li/composite polymer-sulfur cathode in a cell of theinvention, it can be seen that the S/PAN cells display significantlylower voltage throughout discharge, which results in a lower energydensity, based on Watt-hours. Thus, the voltage behavior displayed bythe composite polymer polymer-sulfur cathode of the invention issuperior to that of the sulfurized PAN-based cathodes.

Example 20

Solid polymer electrolyte samples were made by mixing SRT802 (LiquidCrystal Polymer) polymer with lithium hydroxide monohydrate, as acompound comprising ion source, in a proportion 2:1, respectively (byweight). DDQ was used a dopant. Weight ratio of polymer to dopant was2:1. Mixtures were heat treated at 325/250° C. for 30 minutes undermoderate pressure (500-1000 PSI). The ionic surface conductivity of thesamples were measured using standard AC-EIS. Samples were sandwichedbetween stainless steel blocking electrodes and placed in test fixture.AC-impedance was recorded in the range from 800 KHz to 100 Hz usingBiologic VSP test system to determine the electrolyte conductivity. Sixsamples were prepared and tested. Average conductivity was 3.7×10⁻⁴ S/cmwith about 19% standard deviation. The results are shown in thefollowing Table 20.1.

TABLE 20.1 Sample Conductivity (S/cm) 1 3.42E−04 2 4.78E−04 3 4.09E−04 42.69E−04 5 3.46E−04 6 4.04E−04 Average 3.75E−04 Standard Deviation7.18E−05 Standard Deviation % 19.2%

Example 21

Solid polymer electrolyte samples were made by mixing SRT900 (LiquidCrystal Polymer) polymer with lithium hydroxide monohydrate, as acompound comprising ion source, in a proportion 2:1, respectively (byweight). DDQ was used a dopant. Weight ratio of polymer to dopant was2:1. Mixtures were heat treated at 325/250 C for 30 minutes undermoderate pressure (500-1000 psi). Samples were sandwiched betweenstainless steel electrodes and placed in test fixture. AC-impedance wasrecorded in the range from 800 KHz to 100 Hz using Biologic VSP testsystem to determine the electrolyte conductivity. Six samples wereprepared and tested. Average conductivity was 1.5×10⁻³ S/cm with about25% standard deviation. The results are shown in the following Table21.1

TABLE 21.1 Sample Conductivity (S/cm) 1 1.14E−03 2 1.39E−03 3 1.59E−03 41.31E−03 5 1.20E−03 6 2.13E−03 Average 1.46E−03 Standard Deviation3.63E−04 Standard Deviation % 24.9%

Example 22

Polymer electrolyte samples were made by mixing polymer and compoundcomprising ion source in various proportions. DDQ was used a dopant.Molar ratio of polymer to dopant was 4.2. Mixtures were heat treated at325/250 C for 30 minutes under moderate pressure (500-1000 psi). Sampleswere sandwiched between stainless steel electrodes and placed in testfixture. AC-impedance was recorded in the range from 800 KHz to 100 Hzusing Biologic VSP test system to determine the electrolyteconductivity.

Results are shown in the table below. High observed conductivitysuggests that the polymer electrolyte can conduct multiple ions,including to Li⁺, K⁺, Na⁺, Ca²⁺, Mg²⁺, Al³⁺, OH⁻ and Cl⁻.

Ion Source Ion Source Wt. % Conductivity (S/cm) Li₂O 33% 1.9E−04 Na₂O33% 4.2E−05 MgO 33% 6.3E−07 CaCl₂ 33% 6.2E−03 MgCl₂ 20% 8.0E−03 AlCl₃15% 2.4E−03 NaOH 50% 1.3E−04 KOH 50% 2.2E−04

Ability to conduct ions other than Li⁺ opens new applications for thepolymer electrolyte. Sodium- and potassium-based energy storage systemsare viewed as alternative to Li-ion, driven primarily by low cost andrelative abundance of the raw materials.

Calcium, magnesium and aluminum conductivity is important developingmultivalent intercalation systems, potentially capable of increasingenergy density beyond capabilities of Li-ion batteries. There is also apossibility to utilize such materials to create power sources with metalanodes, more stable and less costly than lithium.

Hydroxyl conductivity is crucial for numerous alkaline chemistries,including Zn/MnO₂, Ni/Zn, Ni—Cd, Ni-MH, Zn-air, Al-air. Polymerelectrolytes conducting hydroxyl ions can be also used in alkaline fuelcells and super capacitors.

While the present invention has been described in conjunction withpreferred embodiments, one of ordinary skill, after reading theforegoing specification, will be able to effect various changes,substitutions of equivalents, and other alterations to that set forthherein. It is therefore intended that the protection granted by LettersPatent hereon be limited only by the definitions contained in theappended claims and equivalents thereof.

What is claimed is:
 1. A method of making a battery electrode for anelectrochemical cell comprising: producing a solid, ionically conductivepolymer material having an ionic conductivity of greater than 1×10⁻⁴S/cm at a room temperature by reacting a base polymer, an ion source,and an electron acceptor; adding an electrochemically active material tothe battery electrode; and mixing the electrochemically active materialwith the solid, ionically conductive polymer material, whereby thebattery electrode is electrochemically active when used in theelectrochemical cell; wherein said ion source further comprises at leastone of LiO₂, Na₂O, MgO, CaO, ZnO, KOH, NaOH, CaCl₂, AlCl₃, MgCl₂, LiTFSI(lithium bis-trifluoromethanesulfonimide), LiBOB (Lithium bis(oxalate)borate) and a combination of at least two of the aforementioned.
 2. Amethod of making a battery electrode for an electrochemical cellcomprising: producing a solid, ionically conductive polymer materialhaving an ionic conductivity of greater than 1×10⁻⁴ S/cm at a roomtemperature by reacting a base polymer, an ion source, and an electronacceptor; adding an electrochemically active material to the batteryelectrode; and mixing the electrochemically active material with thesolid, ionically conductive polymer material, whereby the batteryelectrode is electrochemically active when used in the electrochemicalcell; wherein said base polymer comprises at least one of a liquidcrystal polymer, a polyether ether ketone (PEEK), a polyphenylenesulphide (PPS), a semicrystalline polymer with a crystallinity index ofgreater than 30%, and a combination of at least two of theaforementioned; and wherein said electron acceptor is oxygen, whereinsaid ion source comprises lithium, and wherein said base polymer ispolyphenylene sulphide (PPS).
 3. A method of making a battery electrodefor an electrochemical cell comprising: producing a solid, ionicallyconductive polymer material having an ionic conductivity of greater than1×10⁻⁴ S/cm at a room temperature by reacting a base polymer, an ionsource, and an electron acceptor; adding an electrochemically activematerial to the battery electrode; and mixing the electrochemicallyactive material with the solid, ionically conductive polymer material,whereby the battery electrode is electrochemically active when used inthe electrochemical cell; further comprising a heating step wherein insaid heating step the electron acceptor is a vapor.